Uterus: release of blood flow during menstruation

What is menstruation?

Menstruation is a flow of blood that is released by the inner lining of the womb of humans and also by most primates. Its cycle is usually 28 days among women, occurring continuously unless interrupted by pregnancy or menopause.


It starts at puberty, most commonly between the ages of 10 and 17. The first menstruation is called menarche, from this moment, the female body becomes able to generate another life.

Some scientists have wondered why the endometrium (inner lining of the uterus, which is richly vascularized tissue) does not stay inside the uterus and regenerate as it does with other parts of the body, such as the skin and digestive system. One of the theories that answers this question explains that menstruation is the defense of the female organism against the invasion of microorganisms that enter the womb together with sperm.

The Menstrual Cycle

At the beginning of each cycle, the uterus is covered internally by a richly vascularized tissue (the endometrium), preparing to receive the embryo that will develop there throughout the gestation period.

If the egg is fertilized by sperm, pregnancy will occur and menstruation will cease during the gestational period. If it does not, all this richly vascularized tissue will be lost through menstruation. Usually this process will occur monthly until a pregnancy occurs, or until ovulation ceases with the arrival of menopause.

In addition to the two factors already mentioned above (pregnancy and menopause), the menstrual cycle may be temporarily interrupted by other factors such as hormonal imbalance, malnutrition, some organic diseases, or even emotional disturbances.

Menstruation is controlled by the hypothalamus (part of the brain that controls the nervous system) and the pituitary or pituitary gland, which is responsible for producing important hormones such as estrogen (which stimulates endometrial formation) and progesterone (which stimulates endometrial maintenance). maintaining pregnancy).

Dysmenorrhea and PMS

Many women suffer from painful and unpleasant symptoms during their menstrual period, such as dysmenorrhea (menstrual cramps) and PMS (premenstrual tension).

Dysmenorrhea occurs by uterine contraction that results in spasms. These are believed to be stimulated by a hormone called prostaglandin (produced mid-cycle). As therapy, oral contraceptives and other types of drugs that reduce the production of this hormone are used.

PMS is another menstrual symptom that also causes suffering in most women. Its most well-known symptoms are some behavioral changes such as increased irritability, anxiety, tension, fatigue, depression, arousal, sadness, change in appetite, etc. In addition to behavioral symptoms, PMS can also cause physical symptoms such as fluid retention, muscle aches, headaches, increased breast tenderness, etc.

Did you know…

The absence of the menstrual period is known as amenorrhea.

IMPORTANT: The information on this page is only a source for research and school work. Therefore, they should not be used for medical advice. To do so, see a doctor for advice and proper treatment.